JPS61219747A - Prevention of efflorescence for cementitious hardened matter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for preventing efflorescence of cement-based cured materials.

(Prior art) Efflorescence of cement-based hardened materials, such as concrete and mortar buildings, is caused when rainwater, etc. that seeps in from the outside evaporates from the inner and outer walls. This is a phenomenon in which the main component is eluted to the surface, which comes into contact with air and becomes insoluble calcium carbonate.
This efflorescence significantly damages the appearance of the building.

This kind of efflorescence phenomenon of cement-based hardened materials (with regard to
Many scholars have been researching this phenomenon for a long time, and the causative behavior has been clarified, but no good method for preventing it has yet been found.

Currently, known methods for preventing efflorescence include (1) addition of a substance that reacts with the efflorescence component, (2) addition of a waterproofing agent, (2) addition of a water-reducing agent, and formation of a surface coating film. ■Fly ash,
Examples include blast furnace slag, water glass, carbonates, etc., and stearates, liquid paraffin, asphalt-based substances, etc. However, all of these have anti-efflorescence C: Although they have some effect, they are not satisfactory.

In addition, the addition of a water reducing agent reduces the interfacial energy, suppresses the cohesive force of cement particles, and aids in dispersion.
It makes it easier to wet the cement, increasing the hydration effect of cement, and reducing the unit amount of water, which makes the entire volume more dense, reduces water movement paths, and reduces the formation of efflorescence. The aim is to However, this effect is also small.

As methods for forming surface coatings, coating and spraying of vinyl chloride, vinylidene chloride, melamine resin, acrylic resin, oil paint-based substances, etc. have been suggested, but the construction work for forming these coatings is difficult. However, high costs cannot be avoided.

(Structure of the Invention) The present inventors have conducted intensive research to solve the disadvantages of the conventional technology, and have arrived at the present invention. ~0
．． 31 [Okibe, U9yl sodium sulfate 0.001-0
．． 02 heavy metal part, and sodium oleate 9m 0-31H
The present invention relates to a method for preventing efflorescence of a cement-based cured product, which is characterized by adding lt part.

Furthermore, the present invention provides a method for preventing efflorescence, which comprises adding water-soluble cellulose ether thereto.

(Effects of the Invention) According to the present invention, excellent effects similar to those of a queen can be obtained without the disadvantages of the conventional technology.

1] The combination of additives used in the present invention has a greater efflorescence inhibiting effect than commercially available efflorescence inhibitors.

2) A cement-based kneaded material with good water retention and workability can be obtained.

3) The cement-based kneaded product according to the present invention can also be used for tiling, and a cured product with good adhesiveness that does not cause efflorescence can be obtained.

4. The cement-based cured product according to the present invention is waterproof, has a small amount of water permeation, slows neutralization, and has excellent durability.

The present invention will be explained in detail below.

In the present invention, it is important to use lucium chloride in combination with sodium 9lyl sulfate, and this synergistic effect achieves the above effects. The amount of calcium chloride added is cement toom
0.05 to 0.3 m per part of te, preferably 9.1 to 1 part
It is a 0.2 heavy responsibility area, and the efflorescence will increase if it is more or less than this range. Calcium chloride is involved in rusting of the reinforcing bars if a cement-based mixed material containing it comes into contact with the reinforcing bars, so calcium chloride should be kept to the minimum necessary level.

The amount of sodium lauryl sulfate added is 0.001 to 0.02 parts by weight, preferably 0.00 parts by weight per 100 parts by weight of cement.
The amount is 2 to 0.01 parts by weight, and amounts other than this amount do not contribute to preventing efflorescence.

The amount of sodium oleate added is 0 to 3 parts by weight per 100 parts of cement, and although it is not considered an essential component, this addition C: provides more waterproofness and improves the efflorescence prevention effect. , Q,) to 2 parts by weight per 100 parts by weight of cement.

Note that even if the amount added is increased by 3 parts by weight or more, the waterproof property hardly changes. If the amount added is increased, it will adversely affect the adhesion of tiles, etc., so it should be kept to a minimum level as long as waterproofness is achieved.

The present invention provides the above-mentioned method for preventing efflorescence by further adding a water-soluble cellulose ether to the above-mentioned components, and the water-soluble cellulose ether used here includes methylcellulose, hydroxyvpropylmethylcellulose, hydroxyethyl ethylcellulose, hydroxyethyl ethylcellulose, Examples include ethyl cellulose and hydroxypropyl cellulose. The addition ratio of these cellulose ethers is 0.01~
0,! 5 m (It is desirable to have a range of 5 m), and excellent effects on water retention, workability, etc. can be seen.

The cement used in the present invention is mainly Portland cement, but other cements such as fly ash cement and blast furnace cement, gypsum, slaked lime, and calcium carbonate are also used.
Wham, bentonite, clay, etc. may be used in combination.

Further, as the aggregate, river sand, mountain sand, silica sand, cold water sand, lightweight aggregate, etc. are used. In addition, as necessary,
Water reducing agents, /L agents, antifoaming agents, hardening accelerators, shrinkage reducing agents, emulsions, fiber substances, etc. may be added.

Next, a specific example will be given.

The following efflorescence test and water absorption 11 (waterproofness) measurements were conducted on cement mortars having the formulations shown in the Example Table. The results were as shown in the table.

[Efflorescence test]

For cement mortar of each composition, a test piece of length x width x thickness = 100 x 1oo x 20fi was prepared, and after curing for 38 minutes, a 10mm thick sample was immersed in water at 7℃ x 5Q%RH.
It was left to stand for 14 days at a wind speed of 0.1 to Q and 'j m for 7 seconds, and efflorescence was observed.

(Efflorescence amount judgment) ◎...None O...Low Δ...Medium ×...Large [Water absorption III (waterproofing) measurement] JI8 R5201 Based on the test piece preparation method for the medium strength test, each cement mortar I: 40X40X1
A fiQm test piece was prepared, and after 5 days, half of the test piece was immersed in water, and the amount of water absorbed (weight %) over time was determined.

However, the abbreviations used in the table are as follows.

o90sH4000: Product name of Shin-Etsu Chemical Co., Ltd., hydroxypropyl methylcellulose

Claims (1)

[Claims] 1. Calcium chloride 0.0 per 100 parts by weight of cement
5-0.3 parts by weight, sodium lauryl sulfate 0.001
~0.02 parts by weight, and 0-3 parts by weight of sodium oleate
Method 2 for preventing efflorescence of cement-based cured products characterized by adding parts by weight of calcium chloride 0.0 per 100 parts by weight of cement
5-0.3 parts by weight, sodium lauryl sulfate 0.001
~0.02 parts by weight, water-soluble cellulose ether 0.01
A method for preventing efflorescence of a cement-based cured product, characterized by adding ~0.5 parts by weight and 0 to 3 parts by weight of sodium oleate.